Secondary battery control apparatus and control method for predicting charging in regenerative braking

ABSTRACT

A battery ECU executes a program that includes the steps of: sensing a vehicle speed; sensing a battery temperature; calculating a battery SOC; calculating, based on the battery temperature and battery SOC, a vehicle speed threshold value for starting charge limiting control; and setting a charge limiting flag for limiting an amount of electric energy to be to be charged even before regenerative braking, if the sensed vehicle speed is higher than the calculated vehicle speed threshold value.

TECHNICAL FIELD

The present invention relates to a technique for extending the lifetimeof a secondary battery incorporated in a vehicle, and in particular, toa technique for limiting electric energy to be charged into a secondarybattery in regenerative braking.

BACKGROUND ART

An electric vehicle, a hybrid vehicle and a fuel-cell vehicle thatobtain driving force by an electric motor incorporate a secondarybattery. In an electric vehicle, electric energy stored in the secondarybattery is used to drive the electric motor in order to drive thevehicle. In a hybrid vehicle, electric energy stored in the secondarybattery is used to drive the electric motor in order to drive thevehicle, and the electric motor assists the engine to drive the vehicle.In a fuel-cell vehicle, electric energy from the fuel cell is used todrive the electric motor in order to drive the vehicle, and electricenergy stored in the secondary battery is used in addition to theelectric energy from the fuel cell to drive the electric motor in orderto drive the vehicle.

Such a vehicle has a function of regenerative braking, which is afunction of causing an electric motor to serve as an electric generatorin braking of the vehicle, so that the kinetic energy of the vehicle isconverted into electric energy to achieve braking. The electric energyconverted here is stored in the secondary battery and reused inacceleration and the like.

As over discharge and overcharge of the secondary battery impair theperformance of the battery and shorten the lifetime, it is necessary toknow the state of charge (SOC, also referred to as remaining capacity)of the secondary battery to control charging and discharging. Inparticular, with respect to the hybrid vehicle where an electricgenerator is driven by a heat engine incorporated in a vehicle togenerate electric energy which is then charged into a secondary battery,the amount of electric energy to be charged is often controlled to be anapproximately intermediate state (50-60%) between a full-charge state(100%) and a no-charge state (0%), so that the secondary battery canaccept regenerated electric energy and also can supply the electricmotor with electric energy immediately on request. For such control andalso to extend the lifetime of the secondary battery, it is necessary toavoid over discharge and overcharge.

A hybrid vehicle control apparatus incorporating an electric energystorage mechanism including such a secondary battery is disclosed inJapanese Patent Laying-Open No. 11-220810. The publication discloses ahybrid vehicle control apparatus that more properly provides control ofan amount of electric energy to be regenerated when the vehicledecelerates, prevents deterioration of the electric energy storagedevice, and executes sufficient assistance in driving when it isnecessary. The hybrid vehicle control apparatus controls a hybridvehicle having an engine rotating a drive axle of the vehicle, a motorassisting the engine in rotating the drive axle with electric energy andhaving a regeneration function of converting kinetic energy of the driveaxle into electric energy, and electric energy storage means forsupplying electric energy to the motor and storing electric energyoutput from the motor. The control apparatus includes traveling statedetecting means for detecting a traveling state of the vehicle includingat least a vehicle traveling speed, remaining capacity detecting meansfor detecting a remaining capacity of the electric energy storage means,and decelerating regenerative control means for controlling an amount ofelectric energy to be regenerated by the electric motor when the hybridvehicle decelerates based on the output of the traveling state detectingmeans. The decelerating regenerative control means includes means forcorrecting the amount of electric energy to be regenerated based on theoutput of the remaining capacity detecting means.

According to the hybrid vehicle control apparatus disclosed in thepublication, the amount of electric energy to be regenerated by themotor when the hybrid vehicle decelerates is controlled based on theoutput of the traveling state detecting means, and the amount ofelectric energy to be regenerated by the motor is corrected based on theremaining capacity of the electric energy storage means. Therefore, thehybrid vehicle control apparatus can more properly provide control of anamount of electric energy to be regenerated when the vehicledecelerates, prevent deterioration of the electric energy storagedevice, and execute sufficient assistance in driving when it isnecessary.

On the other hand, according to the hybrid vehicle control apparatusdisclosed in the publication, the an amount of electric energy to beregenerated is corrected based on the remaining capacity of the electricenergy storage means. Here, when the remaining capacity of the electricenergy storage means is smaller than a first prescribed remainingcapacity, or when it is smaller than a second prescribed remainingamount that is greater than the first prescribed remaining amount and alatest integrated discharged amount is greater than a prescribeddischarged amount, a regenerated quantity increasing correctivecoefficient (>1.0) is calculated in accordance with a vehicle speed,whereby a decelerating regenerative quantity is corrected to increase.In other words, when the remaining capacity of the electric energystorage means is small, the decelerating regenerative quantity iscorrected to increase so that greater regenerative electric energy isobtained. If a secondary battery (in particular, a nickel-metal hydridebattery) that is one of the electric energy storage means iscontinuously charged with great power for a long period duringregenerative braking operation, the temperature of the batteryincreases, whereby the battery is deteriorated and its lifetime isshortened. Further, increase in the temperature of the battery maydecrease an amount of electric energy to be fully charged. Thus, evenwhen the energy is actually charged only for low SOC, it may bedetermined that the SOC is high. Then the regenerative power may not beaccepted and the fuel economy may be impaired.

If the amount of electric energy to be charged is controlled to belimited after sensing a large amount of input electric energy, thevehicle is decelerated not through engine braking or wheel braking butthrough regenerative braking (a motor/generator generates electricity)until such limiting is started. Here, if the amount of electric energyto be charged into the secondary battery is limited as it is excessivelygreat, from that time point the regenerative braking is limited and thevehicle is decelerated through engine braking or wheel braking. Here,the automatic transmission automatically downshifts the gear in order tomore strongly exert engine braking in the middle of deceleration wherebythe engine speed is increased, or a brake control computer more stronglyexerts wheel braking. Thus, while the driver is depressing the brakepedal in the same manner, he/she may feel awkwardness.

DISCLOSURE OF THE INVENTION

The present invention has been made to solve the aforementionedproblems, and an object thereof is to provide a control apparatus and acontrol method for a secondary battery that controls an amount ofelectric energy to be charged in regenerative braking, so that thelifetime of the secondary battery incorporated in a vehicle is extended.

A control apparatus for a secondary battery according to an aspect ofthe present invention controls a secondary battery incorporated in avehicle. The control apparatus includes: a sensing portion sensing astate quantity related to travel of the vehicle; a predicting portionpredicting, ascribable to the state quantity, a degree of deteriorationof the secondary battery due to charging in regenerative braking of thevehicle; and a limiting portion limiting, based on the predicted degreeof deterioration, an amount of electric energy to be charged in theregenerative braking.

According to the present invention, in a hybrid vehicle, an electricvehicle and a fuel-cell vehicle that incorporate a motor/generator inorder to assist an engine with the motor or in order to regenerateelectric energy with the generator in regenerative braking, a statequantity related to the vehicle is sensed during travel of the vehicle.Here, for example a traveling speed of the vehicle, an amount ofelectric energy charged/discharged along the traveling and the like aresensed. When the speed, that is the state quantity of the vehicle, ishigh (for example, when the vehicle is cruising on a highway at a highspeed), if the brake is actuated at the high speed thereafter, greatregenerative braking electric energy is generated. If the secondarybattery is charged with such great electric energy (great current), thebattery is placed under great load and its temperature increases. Theincrease in the battery temperature promotes early deterioration of thebattery. In light of such points, the predicting portion predicts adegree of deterioration of the secondary battery due to charging inregenerating braking of the vehicle. The limiting portion limits anamount of electric energy to be charged in regenerative braking. Thus,when deterioration of the battery is predicted based on the statequantity related to the travel of the vehicle, the amount of electricenergy to be charged into the secondary battery in regenerative brakingis limited so that an excessive increase in the battery temperature isprevented. Here, when limitation by the limiting portion is performedbefore the regenerative braking is started, there is no switching fromregenerative braking to mechanical braking (downshifting and actuatingengine braking and increasing wheel brake pressure) after the braking isstarted, the driver may not feel awkwardness. As a result, a controlapparatus for a secondary battery controlling an amount of electricenergy to be charged in regenerative braking so that the secondarybattery incorporated in a vehicle can be provided.

Preferably, the predicting portion predicts a degree of deteriorationascribable to an increase in temperature of the secondary battery.

According to the present invention, based on a degree of deteriorationalong an increase in the temperature of the secondary battery, theamount of electric energy to be charged into the secondary battery islimited, and whereby an excessive increase in the temperature of thebattery is suppressed and the lifetime of the secondary battery can beextended.

Further preferably, the predicting portion predicts the degree ofdeterioration to be higher as the increase in temperature of thesecondary battery is predicted to be higher.

According to the present invention, the degree of deterioration isexpected to be higher as the increase in the temperature of the batteryis expected to be higher, and an amount of electric energy to beregenerated for the secondary battery is limited, and whereby anexcessive increase in the temperature of the battery is suppressed andthe lifetime of the secondary battery can be extended.

Further preferably, the sensing portion senses a vehicle speed of thevehicle. The predicting portion predicts the degree of deterioration tobe higher as the vehicle speed is higher.

According to the present invention, when the vehicle speed is high, itis predicted that great regenerative braking electric energy isgenerated if thereafter brake is actuated at high speed. If thesecondary battery is charged with such great electric energy (greatcurrent), the battery is placed under great load and its temperatureincreases, which promotes early deterioration of the battery.Accordingly, it is predicted that the degree of deterioration to behigher as the vehicle speed is higher, and the amount of electric energyto be charged into the secondary battery in regenerative braking of thevehicle is limited.

Further preferably, the sensing portion senses a vehicle speed of thevehicle. The predicting portion predicts the degree of deterioration tobe high when a period during which the vehicle speed is higher than apredetermined speed lasts longer than a predetermined period.

According to the present invention, when the period where the vehiclespeed is high lasts, it is predicted that great regenerative brakingelectric energy is generated if thereafter brake is actuated at highspeed. Accordingly, it is predicted that the degree of deterioration tobe higher when a period during which the vehicle speed is higher than apredetermined speed lasts longer, and the amount of electric energy tobe charged into the secondary battery in regenerative braking of thevehicle is limited.

Further preferably, the sensing portion senses a vehicle speed of thevehicle. The predicting portion predicts the degree of deterioration tobe high when a period during which the vehicle speed is higher than apredetermined speed continuously lasts longer than a predeterminedperiod.

According to the present invention, when the period where the vehiclespeed is high continuously lasts long, it is predicted that greatregenerative braking electric energy is generated if thereafter brake isactuated at high speed. Accordingly, it is predicted that the degree ofdeterioration to be higher when a period during which the vehicle speedis higher than a predetermined speed lasts longer, and the amount ofelectric energy to be charged into the secondary battery in regenerativebraking is limited. In such a case, when the period where the vehiclespeed lasts not continuously (when the vehicle speed is highmomentarily), the amount of electric energy to be charged into thesecondary battery in regenerative braking is not limited and thesecondary battery is charged with the regenerated electric energy.

Further preferably, the sensing portion senses a vehicle speed of thevehicle. The predicting portion predicts the degree of deterioration tobe high when a frequency of the vehicle speed being higher than apredetermined speed is higher than a predetermined frequency.

According to the present invention, when a frequency that the vehiclespeed is high (the number of times the vehicle speed becomes high in apredetermined period) is high, if the brake is actuated at the highspeed thereafter, it is predicted that great regenerative brakingelectric energy may likely be generated. Accordingly, it is predictedthat the degree of deterioration to be higher as a frequency of thevehicle speed being higher than a predetermined speed is higher, and theamount of electric energy to be charged into the secondary battery inregenerative braking is limited. In such a case, when the period wherethe vehicle speed lasts not continuously, the amount of electric energyto be charged into the secondary battery in regenerative braking is notlimited and the secondary battery is charged with the regeneratedelectric energy.

Further preferably, the sensing portion senses an amount of electricenergy to be charged into the secondary battery. The predicting portionpredicts the degree of deterioration to be high when a period duringwhich the amount of electric energy to be charged is greater than apredetermined amount of electric energy lasts longer than apredetermined period.

According to the present invention, the sensing portion senses theamount of electric energy to be charged into the secondary battery asthe state quantity related to the travel of the vehicle. It is predictedthat the degree of deterioration is higher as the period where theamount of electric energy to be charged into the secondary battery isgreat lasts longer, since an excessive increase in the temperature ofthe secondary battery is likely. Thus, the amount of electric energy tobe charged into the secondary battery is limited.

Further preferably, the sensing portion senses an amount of electricenergy to be charged into the secondary battery. The predicting portionpredicts the degree of deterioration to be high when a period duringwhich the amount of electric energy to be charged is greater than apredetermined amount of electric energy continuously lasts longer than apredetermined period.

According to the present invention, the sensing portion senses theamount of electric energy to be charged into the secondary battery asthe state quantity related to the travel of the vehicle. It is predictedthat the degree of deterioration is higher as the period where theamount of electric energy to be charged into the secondary battery isgreat continuously lasts longer, since an excessive increase in thetemperature of the secondary battery is likely. Thus, the amount ofelectric energy to be charged into the secondary battery is limited.

Further preferably, the sensing portion senses an amount of electricenergy to be charged into the secondary battery. The predicting predictsthe degree of deterioration to be high when a frequency of the amount ofelectric energy to be charged being greater than a predetermined amountof electric energy is higher than a predetermined frequency.

According to the present invention, the sensing portion senses theamount of electric energy to be charged into the secondary battery asthe state quantity related to the travel of the vehicle. It is predictedthat the degree of deterioration is higher as the frequency where theamount of electric energy to be charged into the secondary battery isgreat is higher, since an excessive increase in the temperature of thesecondary battery is likely. Thus, the amount of electric energy to becharged into the secondary battery is limited.

Further preferably, the predicting portion predicts a degree ofdeterioration of the secondary battery due to charging in regenerativebraking of the vehicle, considering a state of the secondary battery.

According to the present invention, when the predicting portion makesdetermination of predicting the degree of deterioration of the secondarybattery, for example it uses a threshold value that is determinedconsidering the remaining capacity (SOC) of the secondary battery, thatis the state of the secondary battery, or the threshold value determinedconsidering the battery temperature of the secondary battery.Accordingly, the limitation on the electric energy to be charged may beloosened when the SOC of the battery is low, and it may be made strictwhen the battery temperature is high.

Further preferably, the control apparatus controls cooling capacity of acooling apparatus based on the predicted degree of deterioration.

According to the present invention, a vehicle incorporating thesecondary battery often incorporates a cooling apparatus for cooling thesecondary battery. The control apparatus increases the cooling capacity(the air volume of the cooling air or the temperature of the coolingair) if the predicted degree of deterioration is great. By increasingthe cooling capacity along with the limitation of the amount of theelectric energy to be charged into the secondary battery, deteriorationof the secondary battery can be suppressed and the lifetime thereof canbe extended.

A control method for a secondary battery according to another aspect ofthe present invention is a control method for a secondary batteryincorporated in a vehicle. The method includes the steps of: sensing astate quantity related to travel of the vehicle; predicting, ascribableto the state quantity, a degree of deterioration of the secondarybattery due to charging in regenerative braking of the vehicle; andlimiting, based on the predicted degree of deterioration, an amount ofelectric energy to be charged in the regenerative braking.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a control block diagram of a vehicle incorporating a batteryECU according to a first embodiment of the present invention.

FIG. 2 is a flow chart showing a control configuration of a programexecuted at the battery ECU according to the first embodiment of thepresent invention.

FIG. 3 shows a state where electric energy to be charged is limited inthe vehicle incorporating the battery ECU according to the firstembodiment of the present invention.

FIG. 4. is a flow chart showing a control configuration of a programexecuted at a battery ECU according to a second embodiment of thepresent invention.

FIG. 5 shows a state where electric energy to be charged is limited inthe vehicle incorporating the battery ECU according to the secondembodiment of the present invention.

FIG. 6 is flow chart showing a control configuration of a programexecuted at a battery ECU according to a third embodiment of the presentinvention.

FIG. 7 shows a state where electric energy to be charged is limited inthe vehicle incorporating the battery ECU according to the thirdembodiment of the present invention.

FIG. 8 is flow chart showing a control configuration of a programexecuted at a battery ECU according to a fourth embodiment of thepresent invention.

FIG. 9 is flow chart showing a control configuration of a programexecuted at a battery ECU according to a fifth embodiment of the presentinvention.

BEST MODES FOR CARRYING OUT THE INVENTION

In the following, referring to the drawings, embodiments of the presentinvention will be described. In the following description, the samereference character is allotted to the same parts. The name and functionthereof are also the same. Accordingly, description thereof is notrepeated.

In the following, description will be given as to an apparatus thatcontrols electric energy to be charged into to the secondary battery,which supplies electric energy to driving devices and auxiliary electricappliances of a vehicle and supplied with electric energy from amotor/generator in regenerative braking. While the type of the secondarybattery is not specifically limited, the secondary battery is assumed tobe a nickel-metal hydride battery in the following description. Theapparatus limiting the electric energy to be charged into the secondarybattery according to the embodiment of the present invention isapplicable to any of the electric vehicle, the hybrid vehicle and thefuel-cell vehicle.

First Embodiment

Referring to FIG. 1, description is given as to a power unit of avehicle including a battery ECU (Electronic Control Unit) 200 thatimplements an apparatus limiting electric energy to be charged into asecondary battery according to the present embodiment. As shown in FIG.1, the power unit of the vehicle includes a nickel-metal hydride battery100 and a battery ECU 200.

To nickel-metal hydride battery 100, a temperature sensor 110 formeasuring the temperature of nickel-metal hydride battery 100, and avoltage sensor 130 for measuring the voltage of nickel-metal hydridebattery 100 are attached. To an output cable or an input cableconnecting nickel-metal hydride battery 100 and a power cable of thevehicle, a current sensor 120 for measuring a charging/dischargingcurrent value is attached.

Battery ECU 200 includes temperature sensor 110, current sensor 120,voltage sensor 130, a vehicle speed signal line, an input/outputinterface 500 connected to an ignition-switch-on signal line and acharge limiting flag signal line, a CPU (Central Processing Unit) 300controlling battery ECU 200, a clock 400, and a memory 600 storingvarious data. A power supply terminal of nickel-metal hydride battery100 is connected to a vehicle power cable to supply electric energy to atraveling motor, auxiliary electric appliances and the like of thevehicle.

A temperature signal sensed by temperature sensor 100 measuring thetemperature of nickel-metal hydride battery 100 is transmitted to CPU300 via input/output interface 500 of battery ECU 200.

A current value sensed by current sensor 120 measuring a chargingcurrent value into nickel-metal hydride battery 100 and a dischargingcurrent value from nickel-metal hydride battery 100 is transmitted toCPU 300 via input/output interface 500 of battery ECU 200. CPU 300 iscapable of calculating SOC by integrating the current values over time.

A voltage value sensed by voltage sensor 130 measuring the voltage ofnickel-metal hydride battery 100 is transmitted to CPU 300 viainput-output interface 500 of battery ECU 200. CPU 300 is capable ofcalculating SOC based on an open circuit voltage (PCV) measured with apredetermined condition, and calculating an electric energy value bymultiplying the voltage value sensed by voltage sensor 130 and thecurrent value sensed by current sensor 120.

Inside battery ECU 200, input/output interface 500, CPU 300, clock 400and memory 600 are connected via internal bus 700, and capable ofconducting data communication with one another. Memory 600 stores aprogram executed at CPU 300, threshold values to be used in the programand the like.

Battery ECU 200 sets the charging limiting flag for limiting electricenergy to be charged into the secondary battery and transmits it to anECU (for example, a hybrid ECU) that controls the motor/generator. Thehybrid ECU controls the motor/generator to limit regenerative electricenergy, and controls air volume or cooling temperature of a cooling fanprovided to the secondary battery.

Referring to FIG. 2, a control configuration of a program executed atCPU 300 of battery ECU 200 that is an apparatus for limiting electricenergy to be charged into a secondary battery according to the presentembodiment will be described.

At step (hereinafter step is abbreviated as S) 100, CPU 300 senses avehicle speed. At S110, CPU 300 senses a battery temperature. At S120,CPU 300 calculates battery SOC.

The vehicle speed at S100 is calculated based on a vehicle speed signalinput via input/output interface 500; the battery temperature sensed atS110 is calculated based on a temperature signal input from temperaturesensor 110 via input/output interface 500; and the battery SOCcalculated at S120 is calculated by integrating current values byintegrating current values based on a current value signal input fromcurrent sensor 120 via input/output interface 500.

At S130, CPU 300 calculates a vehicle speed threshold value for startingcharge limiting control based on the battery temperature and the batterySOC. Here, it is calculated so that the vehicle speed threshold value islower as the battery temperature is higher; and the vehicle speedthreshold value is higher as the battery SOC is lower.

At S140, CPU 300 determines as to whether or not the sensed vehiclespeed is higher than the calculated vehicle speed threshold value. Ifthe sensed vehicle speed is higher than the calculated vehicle speedthreshold value (YES at S140), then the process goes to S150. Otherwise(NO at S140), the process goes to S160.

At S150, CPU 300 sets charge limiting flag for limiting an amount ofelectric energy to be charged in regeneration.

At S160, CPU 300 resets charge limiting flag for limiting an amount ofelectric energy to be charged in regeneration.

At S170, CPU 300 determines as to whether or not an ignition switch isturned off. This determination is made based on an ignition-switch-onsignal input via input/output interface 500. If ignition switch isoff(YES at S170), then the process ends. Otherwise (NO at S170), theprocess goes back to S100 and the process steps of S100-S170 arerepeatedly performed.

An operation of a vehicle incorporating battery ECU 200 according to thepresent embodiment based on the above-described structure and flowchartwill be described. When the vehicle is traveling, a vehicle speed issensed (S100), a battery temperature is sensed (S110), and currentvalues sensed by current sensor 120 sensing the current passing throughnickel-metal hydride battery 100 are integrated, whereby a battery SOCis calculated (S120). Based on the battery temperature and the batterySOC, a vehicle speed threshold value for starting charge limitingcontrol is calculated (S130). If the sensed vehicle speed is higher thanthe calculated vehicle speed threshold value (YES at S140), then acharge limiting flag limiting an amount of electric energy to be chargedin regeneration is set (S150). Such a process is repeatedly performed aslong as the ignition switch is turned off, that is, as long as thevehicle is traveling.

FIG. 3(A) shows the change of the vehicle speed over time, whereas FIG.3(B) shows the change of the amount of electric energy to be chargedover time. As shown in FIG. 3(A), in a vehicle incorporating the batteryECU according to the present embodiment, at the time point where avehicle speed exceeds a vehicle speed threshold value, control to limitthe amount of electric energy to be charged is provided. Specifically, acharge limiting flag is set (S150), and based on the charge limitingflag being set, for example a hybrid ECU provides control to limit theamount of electric energy to be regenerated.

As above, according to the battery ECU according to the presentembodiment, based on the battery temperature and the battery SOC, avehicle speed threshold value for starting charge limiting control iscalculated. If the vehicle speed exceeds the vehicle speed thresholdvalue, then great regenerated electric energy is charged into thenickel-metal hydride battery in regenerative breaking, which may rapidlyincrease the temperature of the nickel-metal hydride battery and causedeterioration of the battery. Accordingly, at the time point where thevehicle speed has exceeded the vehicle speed threshold value and beforeregenerative braking is started, the charge limiting flag is set tolimit the amount of electric energy to be charged into the nickel-metalhydride battery. Thus, an excessive increase in the temperature of thenickel-metal hydride battery can be suppressed, deterioration thereofcan be prevented, and the lifetime thereof can be extended.

Second Embodiment

In the following, description is given as to an apparatus limiting anamount of electric energy to be charged into a secondary batteryaccording to a second embodiment of the present invention. The presentembodiment is implemented with the same hardware configuration (controlblock diagram) as the above-described first embodiment. It is differentfrom the first embodiment only in that the program executed at CPU 300of battery ECU 200 is different. Accordingly, detailed descriptionexcept for that is not repeated here.

Referring to FIG. 4, description is given as to a control configurationof a program executed at CPU 300 of battery ECU 200 that is an apparatuslimiting an amount of electric energy to be charged into a secondarybattery according to the present embodiment. In the flow chart of FIG.4, the same step numbers are allotted to the same process steps as inthe flow chart shown in the above-described FIG. 2. The process thereofis also the same. Accordingly, detailed description is not repeatedhere.

At S200, CPU300 initializes a high-speed lasting time VT. It is notedthat high-speed lasting time VT is treated as a variable in CPU 300.

At S210, high-speed lasting time VT is integrated. At S220, based on thebattery temperature and the battery SOC, a high-speed lasting timethreshold value VT(TH) for starting charge limiting control iscalculated. Here, it is calculated so that high-speed lasting timethreshold value VT(TH) is lower as the battery temperature is higher,and high-speed lasting time threshold value VT(TH) is higher as batterySOC is lower.

At S230, CPU 300 determines as to whether or not integrated high-speedlasting time VT is greater than calculated high-speed lasting timethreshold value VT(TH). If high-speed lasting time VT is higher thanhigh-time continuing time threshold value VT(TH) (YES at S230), then theprocess goes to S240. Otherwise (NO at S230), the process goes to S250.

At S240, CPU 300 sets a charge limiting flag for limiting an amount ofelectric energy to be charged in regeneration, after a predeterminedtime has elapsed.

At S250, CPU 300 resets the charge limiting flag for limiting an amountof electric energy to be charged in regeneration.

An operation of a vehicle incorporating battery ECU 200 according to thepresent embodiment based on the above-described structure and flowchartwill be described.

When the ignition switch is turned on, high-speed lasting time VT isinitialized (S200). The vehicle speed is sensed (S100). If the vehiclespeed is higher than the vehicle speed threshold value (YES at S140),high-speed lasting time VT is integrated (S210). Here, when the vehiclespeed is at least at the vehicle speed threshold value (NO at S140),then high-speed lasting time VT is initialized (S200). In other words,high-speed lasting time VT is integrated as long as the vehicle speed ishigher than the vehicle speed threshold value, and high-speed lastingtime VT is initialized once the vehicle speed is at least at the vehiclespeed threshold value.

High-speed lasting time threshold value VT(TH) for starting chargelimiting control is calculated based on the battery temperature and thebattery SOC (S220). If integrated high-speed lasting time VT is greaterthan calculated high-speed lasting time threshold value VT(TH) (YES atS230), after a predetermined time has elapsed, a charge limiting flagfor limiting an amount of electric energy to be charged in regenerationis set (S240).

FIG. 5(A) shows the change of the vehicle speed over time, whereas FIG.5(B) shows the change of the amount of electric energy to be chargedover time. As shown in FIG. 5(A), if a vehicle speed greater than thevehicle speed threshold value is greater than high-speed lasting timethreshold value VT(TH), then after a predetermined time has elapsed fromthat time point, a charge limiting flag for limiting an amount ofelectric energy to be charged is set. Thus, as shown in FIG. 5(B), anamount of electric energy to be charged into nickel-metal hydridebattery 100 is limited.

As above, according to the battery ECU according to the presentembodiment, if a state where a vehicle speed is continuously greaterthan the vehicle speed threshold value is greater than high-speedlasting time threshold value VT(TH) calculated based on the batterytemperature and the battery SOC, control is provided so as to limit theamount of electric energy to be charged in regeneration. Specifically,when a state where the vehicle speed is high continues, greatregenerated electric energy is charged into the nickel-metal hydridebattery in the regeneration braking that follows. Accordingly, a chargelimiting flag for limiting an amount of electric energy to be charged inregeneration is set in advance, so that a certain limit is placed on theamount of electric energy to be charged. As a result, the nickel-metalhydride battery will not be charged with great electric energy and anexcessive increase in the temperature of the nickel-metal hydridebattery is prevented. Thus, deterioration of the nickel-metal hydridebattery can be prevented and the lifetime thereof can be extended.

It is noted that, in the flow chart of FIG. 4, when NO at S140, theprocess may not go back to S200 but may go back to S100. Thus, not onlywhen the vehicle speed is continuously higher than the vehicle speedthreshold value, but also when the vehicle speed temporarily drops andwhen the state where the vehicle speed is higher than the vehicle speedthreshold value intermittently lasts, control can be provided so as tolimit the amount of electric energy to be charged in regenerativebraking.

Third Embodiment

In the following, description will be given as to an apparatus forlimiting an amount of electric energy to be charged into a secondarybattery according to a third embodiment of the present invention.Similarly to the above-described second embodiment, the hardwareconfiguration (control block diagram) thereof is the same as in theabove-described first embodiment. Accordingly, detailed descriptionthereof is not repeated here.

Referring to FIG. 6, description is given as to a control configurationof a program executed at CPU 300 of battery ECU 200 according to thepresent embodiment. In the flow chart of FIG. 6, the same step numbersare allotted to the same process steps as in the flow chart shown in theabove-described FIGS. 2 and 4. The process thereof is also the same.Accordingly, detailed description is not repeated here.

At S300, CPU 300 initializes high-speed traveling frequency α. It isnoted that high-speed traveling frequency α is treated as a variable inCPU 300.

At S310, CPU 300 adds 1 to frequency α. At S320, CPU 300 determineswhether or not the time to measure frequency α has passed. If the timeto measure frequency α has passed (YES at S320), the process goes toS110. Otherwise (NO at S320), the process goes back to S100.

At S330, CPU 300 calculates high-speed traveling frequency thresholdvalue α(TH) for starting charge limiting control, based on the batterytemperature and battery SOC. At S340, CPU 300 determines as to whetheror not calculated frequency α is greater than calculated frequencythreshold value α(TH). If calculated frequency α is greater thancalculated frequency threshold value α(TH) (YES at S340), the processgoes to S240. Otherwise (NO at S340), the process goes to S250.

An operation of a vehicle incorporating battery ECU 200 according to thepresent embodiment based on the above-described structure and flowchartwill be described.

When the ignition switch is turned on, high-speed traveling frequency ais initialized (S300). A vehicle speed is sensed while the vehicle istraveling (S100). If the vehicle speed is higher than the vehicle speedthreshold value (YES at S140), then 1 is added to frequency α (S310).Until the time to measure frequency α passes, such process steps arerepeatedly performed.

When the time to measure frequency α passes (YES at S320), a batterytemperature is sensed (S110), a battery SOC is calculated (S120), andhigh-speed traveling frequency threshold value α(TH) for starting chargelimiting control is calculated based on the battery temperature and thebattery SOC (S330). When calculated frequency α is greater thancalculated high-speed traveling frequency threshold value α(TH), after apredetermined time, a charge limiting flag for limiting an amount ofelectric energy to be charged in regeneration is set (S240).

FIG. 7(A) shows the change of the vehicle speed over time, whereas FIG.7(B) shows the change of the amount of electric energy to be chargedover time. As shown in FIG. 7(A), high-speed traveling frequency α,which is the frequency where the vehicle speed is higher than thevehicle speed threshold value, is measured. When frequency α is greaterthan high-speed traveling frequency threshold value α(TH) (YES at S340),then after a predetermined time from that time point, a charge limitingflag for limiting an amount of electric energy to be charged inregeneration is set (S240), and the amount of electric energy to becharged is limited as shown in FIG. 7(B).

As above, according to the battery ECU according to the presentembodiment, based on the high-speed traveling frequency, when thefrequency is high, control is provided so as to limit the amount ofelectric energy to be charged in regeneration. The frequency of thevehicle speed being higher than the vehicle speed threshold value meansthat great regenerative electric energy is likely to be generated inregenerative braking after the high-speed travel. Accordingly, theamount of electric energy to be charged into the nickel-metal hydridebattery is limited in advance. Thus, an excessive increase in thetemperature of the nickel-metal hydride battery can be suppressed,deterioration thereof can be prevented, and the lifetime thereof can beextended.

Fourth Embodiment

In the following, description is given as to an apparatus limiting anamount of electric energy to be charged into a secondary batteryaccording to a fourth embodiment. Similarly to the above-describedsecond and third embodiments, the hardware configuration (control blockdiagram) thereof is the same as in the above-described first embodiment.Accordingly, detailed description thereof is not repeated here.

Referring to FIG. 8, description is given as to a control configurationof a program executed at CPU 300 of battery ECU 200 according to thepresent embodiment. In the flow chart of FIG. 8, the same step numbersare allotted to the same process steps as in the flow chart shown in theabove-described FIG. 2. The process thereof is also the same.Accordingly, detailed description is not repeated here.

At S400, CPU 300 initializes great electric energy charging time T. Itis noted that great electric energy charging time T is treated as avariable in CPU 300.

At S410, CPU 300 senses a value of electric energy charged byregenerative electric energy. Here, CPU 300 senses the value of electricenergy charged by regenerative electric energy based on a current valuesensed by current sensor 120 and a voltage value sensed by a voltagesensor 130.

At S420, CPU 300 determines as to whether or not the sensed value ofelectric energy charged is greater than a predetermined electric energythreshold value. If the sensed value of electric energy charged isgreater than the predetermined electric energy threshold value (YES atS420), then the process goes to S430. Otherwise (NO at S420), theprocess goes back to S400.

At S430, CPU 300 integrates great electric energy charging time T. AtS440, CPU 300 calculates great electric energy charging time thresholdvalue T(TH) for starting charge limiting control, based on the batterytemperature and the battery SOC. At S450, CPU 300 determines as towhether or not integrated great electric energy charging time T isgreater than calculated great electric energy charging time thresholdvalue T(TH). If integrated great electric energy charging time T isgreater than calculated great electric energy charging time thresholdvalue T(TH) (YES at S450), then the process goes to S460. Otherwise (NOat S450), the process goes to S470.

At S460, CPU sets a charge limiting flag for limiting an amount ofelectric energy to be charged. At S470, CPU 300 resets the chargelimiting flag for limiting an amount of electric energy to be charged.

An operation of a vehicle incorporating battery ECU 200 according to thepresent embodiment based on the above-described structure and flowchartwill be described.

When the ignition switch is turned on, great electric energy chargingtime T is initialized (S400). A value of electric energy charged byregenerative electric energy is sensed (S410). When the sensed value ofelectric energy charged is greater than a predetermined electric energythreshold value (YES at S420), great electric energy charging time T isintegrated (S430). Based on the battery temperature and the battery SOC,great electric energy charging time threshold value T(TH) is calculated(S440). If the calculated great electric energy charging time T isgreater than great electric energy charging time threshold value T(TH)(YES at S450), the charge limiting flag is set (S460).

On the other hand, if calculated great electric energy charging time Tis at least at great electric energy charging time threshold value T(TH)(NO at S450), the charge limiting flag is reset (S470). Such processingsteps are repeatedly performed until the ignition switch is turned off(YES at S170).

Thus, battery ECU 200 senses the value of electric energy charged byregenerative electric energy based on the current value sensed bycurrent sensor 120 and the voltage value sensed by voltage sensor 130(S410), and integrates great electric energy charging time T where thevalue of electric energy charged is greater than the predeterminedelectric energy threshold value (S430). When integrated great electricenergy charging time T is greater than great electric energy chargingtime threshold value T(TH) calculated based on the battery temperatureand the battery SOC, the charge limiting flag is set (YES at S450,S460).

As above, according to the battery ECU of the present embodiment, thevalue of electric energy charged into the-nickel-metal hydride batteryby regenerative energy is sensed. Great electric energy charging time T,where the value of electric energy charged is greater than thepredetermined electric energy threshold value, is integrated andcalculated. When integrated great electric energy charging time T isgreater than great electric energy charging time threshold value T(TH)calculated based on the battery temperature and the battery SOC, chargelimiting control is executed. As a result, limitation on charging isexecuted by the time in which the amount of electric energy charged intothe nickel-metal hydride battery is great lasts. As a result, anexcessive increase in the temperature of the nickel-metal hydridebattery can be suppressed, deterioration thereof can be prevented, andthe lifetime thereof can be extended.

Fifth Embodiment

In the following, description is given as to an apparatus limiting anamount of electric energy to be charged into a secondary batteryaccording to a fifth embodiment of the present invention. Similarly tothe above-described second to fourth embodiments, the hardwareconfiguration (control block diagram) thereof is the same as in theabove-described first embodiment. Accordingly, detailed descriptionthereof is not repeated here.

Referring to FIG. 9, description is given as to a control configurationof a program executed at CPU 300 of battery ECU 200 according to thepresent embodiment. In the flow chart of FIG. 9, the same step numbersare allotted to the same process steps as in the flow chart shown in theabove-described FIG. 8. The process thereof is also the same.Accordingly, detailed description is not repeated here.

At S500, CPU 300 initializes great electric energy charging frequency β.It is noted that great electric energy charging frequency β is treatedas a variable in CPU 300.

At S510, CPU 300 adds 1 to frequency β. At S520, CPU 300 determines asto whether or not a time to measure frequency β has passed. If the timeto measure frequency β has passed (YES at S520), the process goes toS110. Otherwise (NO at S520), the process goes back to S410.

At S530, CPU 300 calculates great electric energy charging frequencythreshold value β(TH) for starting charge limiting control, based on thebattery temperature and the battery SOC. At S540, CPU 300 determines asto whether great electric energy charging frequency β is greater thancalculated great electric energy charging frequency threshold valueβ(TH). If great electric energy charging frequency β is greater thancalculated great electric energy charging frequency threshold valueβ(TH) (YES at S540), then the process goes to S460. Otherwise (NO atS540), the process goes to S470.

An operation of a vehicle incorporating battery ECU 200 according to thepresent embodiment based on the above-described structure and flowchartwill be described.

When the ignition switch is turned on, great electric energy chargingfrequency β is initialized (S500). A value of electric energy to becharged by regenerative electric energy is sensed (S410). If the valueof electric energy to be charged is greater than the electric energythreshold value (YES at S420), 1 is added to frequency β (S510). Untilthe time to measure frequency β has passed (NO at S520), the processsteps are repeatedly performed.

When the time to measure frequency β has passed, a battery temperatureis sensed (S110), and a battery SOC is calculated (S120). Based on thebattery temperature and the battery SOC, great electric energy chargingfrequency threshold value β(TH) is calculated (S530). When greatelectric energy charging frequency β is greater than calculated greatelectric energy charging frequency threshold value β(TH) (YES at S540),the charge limiting flag limiting an amount of electric energy to becharged is set (S460).

As above, according to the battery ECU of the present embodiment, avalue of electric energy to be charged into the nickel-metal hydridebattery is sensed. When the frequency, where value of electric energy tobe charged is greater than an electric energy threshold value, isgreater than a threshold value, control is exerted so as to limit theamount of electric energy to be charged. As a result, an excessiveincrease in the temperature of the nickel-metal hydride battery can besuppressed, deterioration thereof can be prevented, and the lifetimethereof can be extended.

While the above-described first to third embodiments relate to controlfor limiting an amount of electric energy to be charged based on avehicle speed, and the above-described fourth and fifth embodimentsrelate to control for limiting an amount of electric energy to becharged based on a value of electric energy charged, the presentinvention is not limited to such embodiments. The first to fifthembodiments may be combined as appropriate to be implemented.

It should be understood that the embodiments disclosed herein areillustrative and non-restrictive in every respect. The scope of thepresent invention is defined by the terms of the claims, rather than thedescription and example above, and is intended to include anymodifications and changes within the scope and meaning equivalent to theterms of the claims.

1. A control apparatus for a secondary battery incorporated in avehicle, comprising: sensing means for sensing a state quantity relatedto travel of said vehicle; predicting means for predicting, ascribableto said state quantity, a degree of deterioration of said secondarybattery due to charging in regenerative braking of said vehicle; andlimiting means for limiting, based on said predicted degree ofdeterioration, an amount of electric energy to be charged in saidregenerative braking.
 2. The control apparatus for a secondary batteryaccording to claim 1, wherein said predicting means includes means forpredicting a degree of deterioration ascribable to an increase intemperature of said secondary battery.
 3. The control apparatus for asecondary battery according to claim 2, wherein said predicting meansincludes means for predicting said degree of deterioration to be higheras the increase in temperature of said secondary battery is predicted tobe higher.
 4. The control apparatus for a secondary battery according toclaim 1, wherein said sensing means includes means for sensing a vehiclespeed of said vehicle, and said predicting means includes means forpredicting said degree of deterioration to be higher as said vehiclespeed is higher.
 5. The control apparatus for a secondary batteryaccording to claim 1, wherein said sensing means includes means forsensing a vehicle speed of said vehicle, and said predicting meansincludes means for predicting said degree of deterioration to be highwhen a period during which said vehicle speed is higher than apredetermined speed lasts longer than a predetermined period.
 6. Thecontrol apparatus for a secondary battery according to claim 1, whereinsaid sensing means includes means for sensing a vehicle speed of saidvehicle, and said predicting means includes means for predicting saiddegree of deterioration to be high when a period during which saidvehicle speed is higher than a predetermined speed continuously lastslonger than a predetermined period.
 7. The control apparatus for asecondary battery according to claim 1, wherein said sensing meansincludes means for sensing a vehicle speed of said vehicle, and saidpredicting means includes means for predicting said degree ofdeterioration to be high when a frequency of said vehicle speed beinghigher than a predetermined speed is higher than a predeterminedfrequency.
 8. The control apparatus for a secondary battery according toclaim 1, wherein said sensing means includes means for sensing an amountof electric energy to be charged into said secondary battery, and saidpredicting means includes means for predicting said degree ofdeterioration to be high when a period during which said amount ofelectric energy to be charged is greater than a predetermined amount ofelectric energy lasts longer than a predetermined period.
 9. The controlapparatus for a secondary battery according to claim 1, wherein saidsensing means includes means for sensing an amount of electric energy tobe charged into said secondary battery, and said predicting meansincludes means for predicting said degree of deterioration to be highwhen a period during which said amount of electric energy to be chargedis greater than a predetermined amount of electric energy continuouslylasts longer than a predetermined period.
 10. The control apparatus fora secondary battery according to claim 1, wherein said sensing meansincludes means for sensing an amount of electric energy to be chargedinto said secondary battery, and said predicting means includes meansfor predicting said degree of deterioration to be high when a frequencyof said amount of electric energy to be charged being greater than apredetermined amount of electric energy is higher than a predeterminedfrequency.
 11. The control apparatus for a secondary battery accordingto claim 1, wherein said predicting means includes means for predictinga degree of deterioration of said secondary battery due to charging inregenerative braking of said vehicle, considering a state of saidsecondary battery.
 12. The control apparatus for a secondary batteryaccording to claim 1, wherein cooling means for cooling said secondarybattery is incorporated in said vehicle, and said control apparatusfurther comprises control means for controlling cooling capacity of saidcooling means based on said predicted degree of deterioration.
 13. Acontrol method for a secondary battery incorporated in a vehicle,comprising the steps of: sensing a state quantity related to travel ofsaid vehicle; predicting, ascribable to said state quantity, a degree ofdeterioration of said secondary battery due to charging in regenerativebraking of said vehicle; and limiting, based on said predicted degree ofdeterioration, an amount of electric energy to be charged in saidregenerative braking.
 14. The control method for a secondary batteryaccording to claim 13, wherein said step of predicting a degree ofdeterioration of said secondary battery includes a step of predicting adegree of deterioration ascribable to an increase in temperature of saidsecondary battery.
 15. The control method for a secondary batteryaccording to claim 14, wherein said step of predicting a degree ofdeterioration of said secondary battery includes a step of predictingsaid degree of deterioration of said secondary battery to be higher asthe increase in temperature of said secondary battery is predicted to behigher.
 16. The control method for a secondary battery according toclaim 13, wherein said step of sensing a state quantity includes a stepof sensing a vehicle speed of said vehicle, and said step of predictinga degree of deterioration of said secondary battery includes a step ofpredicting said degree of deterioration to be higher as said vehiclespeed is higher.
 17. The control method for a secondary batteryaccording to claim 13, wherein said step of sensing a state quantityincludes a step of sensing a vehicle speed of said vehicle, and saidstep of predicting a degree of deterioration of said secondary batteryincludes a step of predicting said degree of deterioration to be highwhen a period during which said vehicle speed is higher than apredetermined speed lasts longer than a predetermined period.
 18. Thecontrol method for a secondary battery according to claim 13, whereinsaid step of sensing a state quantity includes a step of sensing avehicle speed of said vehicle, and said step of predicting a degree ofdeterioration of said secondary battery includes a step of predictingsaid degree of deterioration to be high when a period during which saidvehicle speed is higher than a predetermined speed continuously lastslonger than a predetermined period.
 19. The control method for asecondary battery according to claim 13, wherein said step of sensing astate quantity includes a step of sensing a vehicle speed of saidvehicle, and said step of predicting a degree of deterioration of saidsecondary battery includes a step of predicting said degree ofdeterioration to be high when a frequency of said vehicle speed beinghigher than a predetermined speed is higher than a predeterminedfrequency.
 20. The control method for a secondary battery according toclaim 13, wherein said step of sensing a state quantity includes a stepof sensing an amount of electric energy to be charged into saidsecondary battery, and said step of predicting a degree of deteriorationof said secondary battery includes a step of predicting said degree ofdeterioration to be high when a period during which said amount ofelectric energy to be charged is greater than a predetermined amount ofelectric energy lasts longer than a predetermined period.
 21. Thecontrol method for a secondary battery according to claim 13, whereinsaid step of sensing a state quantity includes a step of sensing anamount of electric energy to be charged into said secondary battery, andsaid step of predicting a degree of deterioration of said secondarybattery includes a step of predicting said degree of deterioration to behigh when a period during which said amount of electric energy to becharged is greater than a predetermined amount of electric energycontinuously lasts longer than a predetermined period.
 22. The controlmethod for a secondary battery according to claim 13, wherein said stepof sensing a state quantity includes a step of sensing an amount ofelectric energy to be charged into said secondary battery, and said stepof predicting a degree of deterioration of said secondary batteryincludes a step of predicting said degree of deterioration to be highwhen a frequency of said amount of electric energy to be charged beinggreater than a predetermined amount of electric energy is higher than apredetermined frequency.
 23. The control method for a secondary batteryaccording to claim 13, wherein said step of predicting a degree ofdeterioration of said secondary battery includes a step of predicting adegree of deterioration of said secondary battery due to charging inregenerative braking of said vehicle, considering a state of saidsecondary battery.
 24. The control method for a secondary batteryaccording to claim 13, wherein a secondary battery cooling apparatus forcooling said secondary battery is incorporated in said vehicle, and saidcontrol method further comprises a step of controlling cooling capacityof said secondary battery cooling apparatus based on said predicteddegree of deterioration.
 25. A control apparatus for a secondary batteryincorporated in a vehicle, comprising: a sensor sensing a state quantityrelated to travel of said vehicle; and an electronic control unitpredicting, ascribable to said state quantity, a degree of deteriorationof said secondary battery due to charging in regenerative braking ofsaid vehicle, and limiting, based on said predicted degree ofdeterioration, an amount of electric energy to be charged in saidregenerative braking.
 26. The control apparatus for a secondary batteryaccording to claim 25, wherein said electronic control unit predicts adegree of deterioration ascribable to an increase in temperature of saidsecondary battery.
 27. The control apparatus for a secondary batteryaccording to claim 26, wherein said electronic control unit predictssaid degree of deterioration to be higher as the increase in temperatureof said secondary battery is predicted to be higher.
 28. The controlapparatus for a secondary battery according to claim 25, wherein saidsensor includes a sensor sensing a vehicle speed of said vehicle, andsaid electronic control unit predicts said degree of deterioration to behigher as said vehicle speed is higher.
 29. The control apparatus for asecondary battery according to claim 25, wherein said sensor includes asensor sensing a vehicle speed of said vehicle, and said electroniccontrol unit predicts said degree of deterioration to be high when aperiod during which said vehicle speed is higher than a predeterminedspeed lasts longer than a predetermined period.
 30. The controlapparatus for a secondary battery according to claim 25, wherein saidsensor includes a sensor sensing a vehicle speed of said vehicle, andsaid electronic control unit predicts said degree of deterioration to behigh when a period during which said vehicle speed is higher than apredetermined speed continuously lasts longer than a predeterminedperiod.
 31. The control apparatus for a secondary battery according toclaim 25, wherein said sensor includes a sensor sensing a vehicle speedof said vehicle, and said electronic control unit predicts said degreeof deterioration to be high when a frequency of said vehicle speed beinghigher than a predetermined speed is higher than a predeterminedfrequency.
 32. The control apparatus for a secondary battery accordingto claim 25, wherein said sensor includes a sensor sensing an amount ofelectric energy to be charged into said secondary battery, and saidelectronic control unit predicts said degree of deterioration to be highwhen a period during which said amount of electric energy to be chargedis greater than a predetermined amount of electric energy lasts longerthan a predetermined period.
 33. The control apparatus for a secondarybattery according to claim 25, wherein said sensor includes a sensorsensing an amount of electric energy to be charged into said secondarybattery, and said electronic control unit predicts said degree ofdeterioration to be high when a period during which said amount ofelectric energy to be charged is greater than a predetermined amount ofelectric energy continuously lasts longer than a predetermined period.34. The control apparatus for a secondary battery according to claim 25,wherein said sensor includes a sensor sensing an amount of electricenergy to be charged into said secondary battery, and said electroniccontrol unit predicts said degree of deterioration to be high when afrequency of said amount of electric energy to be charged being greaterthan a predetermined amount of electric energy is higher than apredetermined frequency.
 35. The control apparatus for a secondarybattery according to claim 25, wherein said electronic control unitpredicts a degree of deterioration of said secondary battery due tocharging in regenerative braking of said vehicle, considering a state ofsaid secondary battery.
 36. The control apparatus for a secondarybattery according to claim 25, wherein a cooling fan for cooling saidsecondary battery is incorporated in said vehicle, and said electroniccontrol unit controls cooling capacity of said cooling fan based on saidpredicted degree of deterioration.